It is odd that chess grandmasters often disagree in their analysis of positions, sometimes even of simple ones, and that a grandmaster can hold his own against an powerful analytic machine such as Deep Blue. The fact that there must exist pure winning strategies for chess is used to construct a control strategy function. It is then shown that chess strategy is equivalent to an autonomous system of differential equations, and conjectured that the system is chaotic. If true the conjecture would explain the forenamed peculiarities and would also imply that there cannot exist a static evaluator for chess.